Here comes the heresy... It has been well over two years since we have suggested the purchase of any Dell systems or servers. A once fine product line has become a victim of bean counter engineering and very poor customer service.
We also have a serious problem with most home users spending above $550 for a laptop. In fact, we have rarely suggested more than "price shopping" for most home laptop systems unless there are compelling needs. (One recent is my own purchase of a HDMI equipped laptop to leave with the big screen for Netflix) For REAL "roadwarriors" I suggest Lenovo systems and they can get pricey but in a business setting their extra measure of reliability is a must. For almost everybody else, (that includes my wife, a teacher, my son, a lawyer, and my daughters, both social workers) I have been satisifed with $400-500 machines from eMachines, Asus, and Acer. Why? Because most people "overbuy" when getting a laptop. Investing more money for features and/or capacity that will never get used is not wise. You end up with a wonderfully remembered "hand-me-down" to kids in three or four years.
Finally, my personal opinion is that a laptop is a very poor choice for a computer unless you absolutely have to have only one system and need it to be mobile. There are adequate systems for home use (internet, word processing, non-serious games) out there complete with printers(for $75 more with a scanners and copier), and 19"flat screens for arouind $450. (Serious gamers whole other story...our hardware guy put together a system for Christmas that a $3,400.00 video board and a $1,500.00 processor... whole thing was over $7500.00 for a 14 yr old kid!) Then buy a $450 laptop for those few times you need mobility and be happy and productive both at home and on the road.
For businesses, look to spend around $800 for quality desktop systems plus the cost of your choice of display.
The advice about maximum memory is very good. Most people should get by with 160 GB hard drives. Put your video and music on an external drive to keep your system running quickly...sorting through 300-400 gigs of music to get to a folder of my documents leads to the "slows". External backups are also good advice. If you have several users at home, there are now NAS (Network Attached Storage) Devices that allow backups from multiple systems so the whole family can take advantage of them.
Lastly, comparison shop from Newegg.com and compusa.com for laptops and desktop systems. Many times our "wholesalers" are unable to beat their price to us.
Enough of my ranting...